Perhaps a grey English fruit lacks carbon (6)
I believe the answer is:
equine
'perhaps a grey' is the definition.
(I know that grey is a type of equine)
'english fruit lacks carbon' is the wordplay.
'english' becomes 'e' (abbreviation).
'fruit' becomes 'quince' (type of fruit).
'lacks' indicates named letters should be taken away.
'carbon' becomes 'C' (chemical symbol).
'quince' with 'c' removed is 'quine'.
'e'+'quine'='EQUINE'
(Other definitions for equine that I've seen before include "like Black Beauty" , "Horse-like" , "Relating to horses" , "Horsy" , "Horsey" .)